Relational Data Model in Tamil (DBMS Course in Tamil) [Class - 15]

******************** In this video tutorial we going to learn what is relational model,concepts and constraints.

Relational data model is the primary data model, which is used widely around the world for data storage and processing. This model is simple and it has all the properties and capabilities required to process data with storage efficiency.

Concepts
→ Tables − In the relational data model, relations are saved in the format of Tables. This format stores the relation among entities. A table has rows and columns, where rows represent records and columns represent the attributes.

→ Tuple − A single row of a table, which contains a single record for that relation is called a tuple.

→ Relation instance − A finite set of tuples in the relational database system represents relation instance. Relation instances do not have duplicate tuples.

→ Relation schema − A relation schema describes the relation name (table name), attributes, and their names.

→ Relation key − Each row has one or more attributes, known as relation key, which can identify the row in the relation (table) uniquely.

→ Attribute domain − Every attribute has some pre-defined value scope, known as attribute domain.

Constraints
Every relation has some conditions that must hold for it to be a valid relation. These conditions are called Relational Integrity Constraints. There are three main integrity constraints −
→ Key constraints
→ Domain constraints
→ Referential integrity constraints

Key Constraints
There must be at least one minimal subset of attributes in the relation, which can identify a tuple uniquely. This minimal subset of attributes is called key for that relation. If there are more than one such minimal subsets, these are called candidate keys.
Key constraints force that −
→ in a relation with a key attribute, no two tuples can have identical values for key attributes.
→ a key attribute can not have NULL values.
Key constraints are also referred to as Entity Constraints.

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Video Credits: Abirami
Disclaimer: Thanks Abirami for contributing this video for this channel. I have paid Abirami for doing this video exclusively for this channel.
birami for doing this video exclusively for this channel.
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